[1] N Carolina State Univ, Intracellular Pathogens Res Lab, Raleigh, NC 27606 USA
[2] N Carolina State Univ, Vet Teaching Hosp, Dept Clin Sci, Raleigh, NC 27606 USA
[3] N Carolina State Univ, Coll Vet Med, Raleigh, NC 27606 USA
[4] Auburn Univ, Coll Vet Med, Auburn, AL 36849 USA
[5] Tufts Univ, Cummings Sch Vet Med, North Grafton, MA USA